Ander Herrera's first-half red card put Manchester United on the back foot as they sought to continue their FA Cup defence with victory over Chelsea.
And the decision was so tough that not even the Red Devils themselves could come to an agreement.
Some fans took to Twitter to slam Michael Oliver for pulling out two bookings for the Spain international in the space of just 15 minutes.
Others chose to single out the midfielder for what were a pair of rather unnecessary fouls - but who is on the money?
That's an idiotic decision from the referee. A fantastic looking FA Cup tie and he's thrown it to the bin. Ander Herrera sees red. — The Man Utd Way (@TheManUtdWay) 13 de marzo de 2017
Conte aggressively cheering Herrera's red card. — Miguel Delaney (@MiguelDelaney) 13 de marzo de 2017
'Mourinho, your thoughts on Ander Herrera's red card?'— Mohamed ElNneny (@ElNnenyM) 13 de marzo de 2017
"Chelsea have an easy schedule because they're not in Europe." pic.twitter.com/XMOF1qloXh